J.Ski, you're the only person in this thread with a vehicle that has a "compact" spare tire incorrectly sized for highway speeds. For everyone else here, the 18" spare tire on these vehicles is literally the exact tire/wheel installed from the factory on the XL trim vehicles and the circumferential difference between them and the 20's and 22's is nearly identical. The sidewall difference will slightly change the handling characteristic but you'd have to be driving quite carelessly for it to have any real detrimental effect.